1. Field of the Invention
The present invention relates to a device for guiding a moving, transversely stable web, in particular a corrugated board web, a corrugated board layer web, a paper web, or a transversely stable foil web.
2. The Prior Art
With a device known from EP-A2-0277761, FIG. 10, for guiding a strip in the winding of transformers, the through-extending guide cylinder extends across approximately half the width of the strip. When, for correction purposes, the guide cylinder is swung, the mechanical stress in the strip is very high at the ends of the long, line-shaped support zone of the guide cylinder. In addition, the guide cylinder has almost no correcting effect with its center zone, so that the strip is twisted locally. Moreover, the guide cylinder is lastingly forcing the strip onto the support, so that in the course of correction, the center zone of the strip acted upon for correction is clamped in an undesirable way across the entire width of the support zone, and the strip is not only braked, or slowed down, but will follow corrections unwillingly under certain circumstances. This may cause damage in the strip.
With another device known from WO-88/01755 for guiding photo printing paper web, the width of the support zone of the one-piece guide cylinder comes to about one-third of the total width of the paper strip. With such a long support zone of the guide cylinder, which is desirable for final corrections, high mechanical stresses occur at the longitudinal ends of the guide cylinder, which on the one hand may lead to damage in the strip and, on the other hand, reduce the corrective effect of the guide cylinder between its ends. Furthermore, during correction and also when running correctly, the strip is clamped between the guide cylinder and the stationary support across the width of the support zone, which means additional mechanical stress is caused in the strip and the displacement of the strip sideways during corrections is made more difficult.
With another type of a device as known from DE-A1-28 44 528 for guiding a strip of photographic paper, the strip of paper runs centrally through a roll gap of two guide cylinders which are pressed against one another, one of which is driven. The width of each guide cylinder conforms to about one-sixth of the width of the strip. For obtaining an adequate corrective effort to some degree with such short guide cylinders, it is necessary to set a highly inclined position and strong clamping, which leads to high mechanical stresses in the strip.